Scripting

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Scripting in Linux is a way to speed up a systems administrator's job. All those tasks that take 5 or 6 commands can be put into a script and even scheduled to run automatically. This week, we're going to write scripts to manipulate images using a utility called ImageMagick.

Day 1 Goal

Get comfortable with the convert command. Try to resize an image and change the file format. For example, try converting a picture to be a "thumbnail" image, 100 pixels wide.

Tasks:
  • Size an image down (-size option)
  • Crop an image (-crop option)
  • Rotate an image (-rotate option)

Resources:
ImageMagick documentation
convert man page

Day 2 Goal

Recreate yesterday's convert command in a shell script. Your script should take an image's filename as input, change the image's size and file format.

Tasks:
  • Write a shell script
  • Make it take input from the commandline
  • Make it executable
  • Make it do everything from Day 1

Day 3 Goal

Adapt your script to batch process an entire directory of images.

Tasks:
  • Resize all images in a directory
  • Rotate all images in a directory

Day 4 Quiz

Quiz on Thursday: write a new shell script based on what you learned this week. I'll give you some images and ask you to do something with them all. What I ask, exactly, is top secret and will be revealed on Thursday.

Day 5 (Monday, Apr. 15)

Putting conditions in your script (if/then statements). Start with this BASH Programming Conditionals page.

Objectives:
  • Describe the basic if/then theory
  • Write an if/then statement for a BASH script (syntax matters!)
  • Adjust a sample program to run all branches of the if/then statement

Day 6

What "else"? Adding the "else" bit into your if/then statements. Return to the BASH Programming Conditionals page to find out how.

Objectives:
  • Describe what "else" does
  • Write a sample script to practice with else

Day 7

Practice some more complex scenarios provided by Megan.

Day 8 (Friday, Apr. 18)

Quiz day!